Preventing lethal showers of glass
SLIVERS of glass falling off buildings on to pedestrians after an explosion, crash, cyclone or earthquake present a higher safety risk these days, with more glass facades on bigger buildings.
Some buildings in Australia are at a much higher risk than other buildings in this country. Buildings in the tropics are more at risk from cyclones and those in earthquake zones are also at higher risk.
So some buildings need to be constructed or reinforced with materials stronger than ordinary plate glass. Laminated glass may be necessary for some new buildings and coated glass for existing buildings.
Bekaert Specialty Films Australia manufactures a range of coatings called Armorgard safety and security window films.
This company explains what happens to glass buildings in an explosion and how films can reduce the risk of death and injury from shattered glass to pedestrians in the street and workers in buildings.
Bekaert says an explosion may result from a terrorist attack or an industrial accident.
An explosion displaces air, creating an overpressure. The overpressure causes a vacuum where the blast pushes air away and generates a shock wave. The shock wave breaks the glass and can turn it into “dagger-like missiles” or atomise it.
A shock wave can knock the air out of a person’s lungs and force him to inhale the atomised glass particles, resulting in death.
The vacuum caused by the explosion is instantly followed by a rush of air back to the origin of the explosion. This implosion sucks the shattered glass out of a building and into the street, causing thousands of lethal glass slivers to rain on people below.
In a skyscraper or other multi-storey building, an explosion may pull a window from its frame.
Bekaert says the ideal time to prevent glass from falling on to people in an explosion is during the construction of a new building. But protective films can be retrofitted to glass in existing buildings.
Transparent film is applied to the interior surface of a window to form an invisible protective coating.
Once installed, the film can stretch without tearing in an explosion and can absorb much of the shock so that broken glass is held intact in the window frame.
Armorgard films are available in different thicknesses to suit specific requirements. They are manufactured with single layers or multiple layers of laminated clear polyester.
Another supplier of glass to Australia, Wright Style in the United Kingdom, has launched a new range of fire-resistant steel glazing.
Wright Style says it has tested its fire-rated glazing extensively in many different applications and has proved it to be cost effective.
Its integrity and insulated range of WSL F-Glass comprises a double-glazed sealed unit, made from two pieces of 5mm toughened float glass, sandwiching a clear UV-stable heat reactive gel. The overall thickness of the glass varies according to the fire rating required and has test certification time periods of up to two hours.
For 30/30. 60/60 and 90/90 applications, WSL F-Glass has been tested up to 3.22sq m, and to 2.6sq m for 120/120 application.
All WSL F-Glass is certified as a Class A safety glass and, the suppler says, it has excellent optical and sound reduction properties.
Write Style’s integrity-only glasses, Fire-Gard and Fire-Gard Lite, are nominally 6mm thick and rated 60/0 and 30/0 respectively. Both are available in a single monolithic form, or as part of a double-glazed sealed unit.
Fire-Gard and Fire-Gard Lite are certified as Class A safety glasses, with a maximum tested size of 3 sq m for Fire-Gard or 3.125sq m for Fire-Gard Lite.
Write Style says its new range complements its extensive range of steel glazing systems covering doors, windows, screens and curtain walling.
4-Feb-2002